CILIA OF STYLONYCHIA 



117 



cylindrical, it is flattened on one the ventral side, 

 and is thus irregularly plano-convex in transverse section 

 (Fig. 22, c). 



It resembles Paramcecium in general structure (compare 



FIG. 22. A, Stylonychia mytihis, ventral aspect, showing the buccal 

 groove (buc. gr.} and mouth (mt/i), two nuclei (mi, nu), contractile 

 vacuole (c.vac), and cilia differentiated into hook-like (h. '), bristle- 

 like (b. ci), plate-like ( p. ci), and fan-like (in. ci) organs. 



B, one of the plate-like cilia of the same (/. ci in A), showing its 

 frayed extremity. 



C, transverse section of Gastrostyla, a form allied to Stylonychia, 

 showing buccal groove (btic. gr.), small dorsal cilia (d. ci}, hook-like 

 cilium (h. ci), and the various cilia of the buccal groove, including an 

 expanded fan-like organ (m. ci). A and B after Claparede and Lach- 

 mann : c after Sterki. 



Fig. 22, A, with Fig. 20, A) ; but owing to the absence of 

 trichocysts the distinction between cortex and medulla is 

 less obvious : moreover, it has two nuclei (//, nu) and only 

 one contractile vacuole (c. vac]. 



